Hand-held nailing tool

ABSTRACT

A handy electric nailing gun includes a firing pin, a firing spring for pushing the firing pin to drive nails into workpiece, an output gear rotatable by a motor through a transmission gear set to retract the firing pin during the first half run of each rotation cycle and to release the firing pin during the second half run of each rotation cycle, and three power switches electrically connected in series between the motor and the power source (AC adapter/rechargeable battery) for operation by the user to control the operation of the motor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electric nailing gun and moreparticularly, to a handy electric nailing gun, which retracts the firingpin during first half run of each rotation cycle of the output gear andrelease the firing pin to drive one nail out of the housing duringsecond half run of each rotation cycle of the output gear.

2. Description of the Related Art

Various power nailing guns have been disclosed, and have appeared on themarket. These power nailing guns are designed to work with an aircompressor. However, an air compressor for this purpose is heavy and nothighly movable. Therefore, conventional power nailing guns are notsuitable for home use.

SUMMARY OF THE INVENTION

The present invention has been accomplished under the circumstances inview. It is therefore the main object of the present invention toprovide an electric nailing gun, which is handy and convenient for homeuse. According to one aspect of the present invention, the handyelectric nailing gun comprises a housing, the housing comprisinghandhold means for holding by hand, an elongated nail chamber adapted toaccommodate nails, the nail chamber having an inner close end and anouter open end, a follower spring installed in the inner close end ofthe nail chamber and adapted to push loaded nails toward the outer openend of the nail chamber, a barrel perpendicularly aimed at the outeropen end of the nail chamber; a power unit, the power unit comprising apower source, a first power switch, and a second power switch, the firstpower switch and the second power switch being electrically connected inseries to the power source and each having a switching rod; atransmission unit, the transmission unit comprising a motor electricallyconnected to the power unit, a transmission gear set rotatable by themotor, and an output gear meshed with the transmission gear set androtatable by the transmission gear set upon operation of the motor, theoutput gear having a series of teeth arranged around a part of theperiphery thereof and a push rod; a striking mechanism controllable bythe transmission unit to drive nails out of the nail chamber, thestriking mechanism comprising a firing pin, the firing pin having alongitudinal rack formed integral with the periphery thereof forengagement with the teeth of the output gear, and a firing springconnected between one end of the firing pin and a part inside thehousing and adapted to push the firing pin toward the outer open end ofthe nail chamber to drive one nail out of the nail chamber afterdisengagement of the rack from the teeth of the output gear; and acontrol unit adapted to control on/off of the power unit, the controlunit comprising a first control button adapted to press the switchingrod of the first power switch and to further switch on the first powerswitch, a second control button adapted to control on/off status of thesecond power switch, a press member coupled to the housing and pressedon the switching rod of the second power switch to switch off the secondpower switch, the press member having an elongated coupling hole coupledto a pivot pin inside the housing, a push block controllable by thesecond control button to move the press member away from the switchingrod of the second power switch and to further switch on the second powerswitch, and a return spring adapted to return the press member after thepress member has been moved away from the switching rod of the secondpower switch by the push block. According to another aspect of thepresent invention, the power source can be an AC adapter or rechargeablebattery, or their combination.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plain view of a handy electric nailing gun according to thepresent invention.

FIG. 2 is similar to FIG. 1 but showing the handy electric nailing gunequipped with an AC adapter.

FIG. 3 is a schematic plain view of the present invention, showing thefirst control button and the second control button of the handy electricnailing gun pressed.

FIG. 4 is similar to FIG. 3 but showing the firing pin retracted.

FIG. 5 is a schematic plain view of the present invention, showing thefiring pin rushed forwards and one nail driven out of the housing.

FIG. 6 is a schematic plain view of the present invention, showing thepress member returned after one firing cycle.

FIG. 7 is a plain view of an alternate form of the handy electricnailing gun according to the present invention.

FIG. 8 is a sectional view taken in an enlarged scale along line A–A′ ofFIG. 7.

FIG. 9 is an enlarged view of part B of FIG. 7.

FIG. 10 is a sectional view taken in an enlarged scale along line C–C′of FIG. 7.

FIG. 11 is similar to FIG. 7 but showing the actuating rod depressed andthe third power switch switched on.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, a handy electric nailing gun in accordance with thepresent invention is shown comprised of a housing 1, a power unit 2, atransmission unit 3, a control unit 4, and a striking mechanism 5.

The housing 1 comprises handhold means, for example, a hand hole 11through which the user can hold the nailing gun with the hand, anelongated nail chamber 12 and a barrel 15 arranged at right angles, afollower spring 14 installed in one end, namely, the inner end of thenail chamber 12 and adapted to push a bar of nails 13 forward toward theother end, namely, the outer end of the nail chamber 12, and alongitudinal slot 151 in one side, namely, the bottom side of the barrel15. The barrel 15 accommodates the striking mechanism 5.

The power unit 2 comprises a power source 21, a first power switch 22,and a second power switch 23. The power source 21 can be an AC adapter(see FIG. 2), or a rechargeable battery (see FIG. 1). The first powerswitch 22 and the second power switch 23 are electrically connected tothe power source 21, each having a switching rod 221 or 231. The firstpower switch 22 is switched on when the switching rod 221 of the firstpower switch 22 is pressed. The second power switch 23 is switched offwhen the switching rod 231 of the second power switch 23 is pressed.Because the circuit design of the power unit 2 is of the known art, nofurther detailed description in this regard is necessary.

The transmission unit 3 comprises a motor 31, a transmission gear set32, and an output gear 33. The motor 31 is electrically connected to thepower unit 2 and controlled to rotate the transmission gear set 32 bythe power unit 2. The transmission gear set 32 is a speed changing(speed reduction) gear set driven by the motor 31 to rotate the outputgear 33. The output gear 33 has teeth 331 arranged around only a part,for example, one half of the periphery, and a push rod 332perpendicularly extended from one side thereof. The output gear 33 isadapted to retract the firing pin 51 of the striking mechanism 5.Therefore, the number of the teeth 331 of the output gear 33 isdetermined subject to the designed retract stroke of the firing pin 51of the striking mechanism 5.

The control unit 4 comprises a first control button 41, a second controlbutton 42, a press member 43, a push block 44, and a return spring 433.The first control button 41 and the second control button 42 arerespectively mounted in the hand hole 11 at one side, each have one end,namely, the first end pivoted to the housing 1 and the other end,namely, the free end supported on a respective spring member 45. Thefirst control button 41 is adapted to drive the switching rod 221 of thefirst power switch 22, thereby switching on the first power switch 22(see FIG. 3). The second control switch 42 has a receiving hole 421formed in the free end and accommodating a spring member 422, whichsupports the push block 44. The push block 44 has a beveled front guideedge 441. The press member 43 is a curved, for example, L-shaped memberhaving an elongated slot 431 formed in a middle part thereof and coupledto a pivot pin 16 inside the housing 1, a locating hole 432 formed inone end thereof and adapted to receive the push block 44. The returnspring 433 is connected between one end of the press member 43 and thehousing 1, holding the press member 43 pressed on the switching rod 231of the second power switch 23 to switch off the second power switch 23(see FIG. 1). The push block 44 is inserted into the locating hole 432of the press member 43, and adapted to move the press member 43 awayfrom the switching rod 231 of the second power switch 23 and to furtherswitch on the second power switch 23 (see FIG. 3). When electricity istransmitting from the power unit 2 to the transmission unit 3, the motor31 is started to rotate the output gear 33 via the transmission gear set32, thereby causing the push rod 332 to push the press member 43. Atthis time, the press member 43 is turned about to the pivot pin 16 todisengage the locating hole 432 from the push block 44 (see FIG. 5), andthe return spring 433 immediately returns the press member 43 to theposition shown in FIG. 1, and therefore the switching rod 231 is pressedto switch off the second power switch 23. After the push rod 332 passedover the press member 43, the press member 43 is turned about the pivotpin 16 in the reversed direction to the position shown in FIG. 6.

The striking mechanism 5 comprises the aforesaid firing pin 51, a tip52, and a firing spring 53. The firing pin 51 is slidably mounted in thebarrel 15, having a rack 511 formed integral with the periphery. Therack 511 is suspended in the longitudinal slot 151 and meshed with theteeth 331 of the output gear 33 (see also FIG. 8). The tip 52 is fixedlyconnected to the front end of the firing pin 51 for driving nails 13 outof the elongated nail chamber 12 into the workpiece. The firing spring53 has the front end axially inserted into the inside of the firing pin51 and fixedly connected thereto and the rear end connected to the innerside of the back wall of the barrel 15 (see FIG. 1).

When the user pressed the first control button 41 and the second controlbutton 42 at the first time (see FIG. 3), the press member 43 is forcedto move by the push block 44, and the return spring 433 is stretched topreserve spring force. At this time, the motor 31 is started to rotatethe transmission gear set 32 and the output gear 33. During rotarymotion of the output gear 33, the teeth 331 of the output gear 33 willbe forced into engagement with the rack 511 of the firing pin 51 to movethe firing pin 51 toward the back side of the barrel 15 (see FIG. 4).After the teeth 331 of the output gear 33 have been moved over the rack511 of the firing pin 51, the firing spring 53 immediately pushes thefiring pin 51 forwards in a rush, thereby causing the tip 52 to driveone nail 13 out of the housing 1 into the workpiece, completing onefiring cycle (see FIG. 5). The output gear 33 is continuously rotatedafter firing of one nail 13. As soon as the push rod 332 of the outputgear 33 touches the press member 43, the press member 43 will be turnedabout the pivot pin 16 to disengage the locating hole 432 from the pushblock 44. Immediately after disengagement of the press member 43 fromthe push block 44, the press member 43 will be returned by the returnspring 433 to press on the switching rod 231 of the second power switch23, thereby switching off power supply. After the push rod 332 of theoutput gear 33 moved over the press member 43, the press member 43 isreleased (see FIG. 6). When the user released the hand from the secondcontrol button 42, the spring member 422 immediately pushes the pushblock 44 into the locating hole 432 again (see FIG. 1), and oneoperation cycle is finished.

FIGS. 7˜11 show an alternate form of the present invention. According tothis alternate form, the rear end of the firing spring 53 is connectedto a locating plate 54, which is threaded onto the threaded shank 55 ofan adjustment screw 55 at the back side of the housing 1. Rotating theadjustment screw 55 clockwise/counter-clockwise causes the locatingplate 54 to move forwards/backwards along the threaded shank 55, andtherefore the spring force of the firing spring 53 is relativelyadjusted. Further, the housing 1 has a hole 17 in the front side toaccommodate a spring member 19 and an actuating rod 18. The actuatingrod 18 is supported on the spring member 19, having an inner end fixedlyconnected to a press rod 10. The spring member 19 supports the actuatingrod 18 in an extended position where the actuating rod 18 has one end,namely, the outer end projecting out of the housing 1. The press rod 10is adapted to press the switching rod 241 of a third power switch 24.When the user pressed the actuating rod 18 against the workpiece, thepress rod 10 is forced to press the switching rod 241 of the third powerswitch 24, thereby switching on the third power switch 24. The user canswitch on the first power switch 22 and the second power switch 23 tostart the transmission unit 3 only after the third power switch 24 hasbeen switched on. The three power switches of the present inventionensure safety operation of the nailing gun.

A prototype of nailing gun has been constructed with the features ofFIGS. 1˜11. The nailing gun functions smoothly to provide all of thefeatures discussed earlier.

Although particular embodiments of the invention have been described indetail for purposes of illustration, various modifications andenhancements may be made without departing from the spirit and scope ofthe invention.

1. A handy electric nailing gun comprising: a housing, said housingcomprising handhold means for holding by hand, an elongated nail chamberadapted to accommodate nails, said nail chamber having an inner closedend and an outer open end, a follower spring installed in the innerclosed end of said nail chamber and adapted to push loaded nails towardthe outer open end of said nail chamber, a barrel perpendicularly aimedat the outer open end of said nail chamber; a power unit, said powerunit comprising a power source, a first power switch, and a second powerswitch, said first power switch and said second power switch beingelectrically connected in series to said power source and each having aswitching rod; a transmission unit, said transmission unit comprising amotor electrically connected to said power unit, a transmission gear setrotatable by said motor, and an output gear meshed with saidtransmission gear set and rotatable by said transmission gear set uponoperation of said motor, said output gear having a series of teetharranged around a part of the periphery thereof and a push rod; astriking mechanism controllable by said transmission unit to drive nailsout of said nail chamber, said striking mechanism comprising a firingpin, said firing pin having a longitudinal rack formed integral with theperiphery thereof for engagement with the teeth of said output gear, anda firing spring connected between one end of said firing pin and a partinside said housing and adapted to push said firing pin toward the outeropen end of said nail chamber to drive one nail out of said nail chamberafter disengagement of said rack from the teeth of said output gear; anda control unit adapted to control on/off of said power unit, saidcontrol unit comprising a first control button adapted to press theswitching rod of said first power switch and to further switch on saidfirst power switch, a second control button adapted to control on/offstatus of said second power switch, a press member coupled to saidhousing and pressed on the switching rod of said second power switch toswitch off said second power switch, said press member having anelongated coupling hole coupled to a pivot pin inside said housing, apush block controllable by said second control button to move said pressmember away from the switching rod of said second power switch and tofurther switch on said second power switch, and a return spring adaptedto return said press member after said press member has been moved awayfrom the switching rod of said second power switch by said push block.2. The handy electric nailing gun as claimed in claim 1, wherein saidfirst control button and said second control button are respectivelysupported on a respective spring member in said housing.
 3. The handyelectric nailing gun as claimed in claim 2, wherein said output gear hasa push rod perpendicularly extended from one side thereof and adapted toturn said press member about the pivot pin inside said housing between afirst position where said press member is maintained engaged with saidpush block and movable away from the switching rod of said second powerswitch by said second control button and a second position where saidpress member is disengaged from said push block and not movable by saidsecond control button; said push block has a beveled front guide edge.4. The handy electric nailing gun as claimed in claim 1, wherein saidbarrel has a longitudinal slot for accommodating said rack of saidfiring pin.
 5. The handy electric nailing gun as claimed in claim 1,wherein said power source is an AC adapter.
 6. The handy electricnailing gun as claimed in claim 1, wherein said power source is arechargeable battery.
 7. The handy electric nailing gun as claimed inclaim 1, wherein said press member has a receiving hole holding a springmember that supports said push block.
 8. The handy electric nailing gunas claimed in claim 1, wherein said control unit further comprises athird power switch electrically connected in series between said powersource and said second power switch, an actuating rod mounted in saidhousing movable in and out of said housing between an on position and anoff position to switch on/off said third power switch, a spring membersupporting said actuating rod in said on position, and a press rodfixedly connected to said actuating rod and movable with said actuatingrod to switch on/off said third power switch.
 9. The handy electricnailing gun as claimed in claim 1, wherein said striking mechanismfurther comprises a locating plate axially movably mounted in a rearside inside said barrel and stopped at one end of said firing springagainst said firing pin, and an adjustment screw mounted in said housingfor rotation by the user to move said locating plate in said barrel andto further adjust the spring force of said firing spring.